The NSW government says industrial action taken by Sydney bus drivers was "disgraceful".
Transport Minister Gladys Berejiklian on Wednesday said bus union officials were kept up-to-date on a July 29 incident when there was a suspected explosion in a gas-powered bus.
The below video, posted on YouTube, purports to be of the same event.
Sydney's peak hour was thrown into disarray on Tuesday afternoon after government bus drivers took almost 700 gas-powered buses off the road, citing safety concerns.
The NSW Rail Tram and Bus Union (RTBU) said it was given video footage on Tuesday of a gas-powered bus catching fire on July 29 in Hillsdale, in Sydney's south which showed it exploded.
However, Ms Berejiklian said the footage had been on YouTube since August 2 and that the RTBU had been kept informed of the
investigation.
"The unions were claiming that this footage mysteriously appeared on their doorstep yesterday morning, which is why they took the industrial action," Ms Berejiklian told Macquarie Radio.
"We actually have evidence last night showing that there was footage of the same incident on August 2, three days after the incident."
The Sydney Transport Authority took "immediate action" after the fire and carried out weekly checks of the 700 gas-powered bus fleet, she said.
An investigation by the independent safety regulator was also underway.
"If there was a risk, those buses wouldn't be on the road," she said.
Ms Berejiklian described the union action as "disgraceful" and said it came at the same time that award negotiations were at a "very delicate stage".
"I was very concerned unions said the STA kept them in dark, that it hadn't kept them involved," she said.
"I received a report last night telling me that the STA kept the union advised over the week of the incident."
"The following Tuesday, two of the very senior union delegates were given a tour of the burnt out bus by the manger of the bus fleet.
"So the STA actually gave the union a tour of the burnt out bus."
